US11542951B2 - Gas compressor and control method therefor - Google Patents

Gas compressor and control method therefor Download PDF

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Publication number
US11542951B2
US11542951B2 US16/978,506 US201916978506A US11542951B2 US 11542951 B2 US11542951 B2 US 11542951B2 US 201916978506 A US201916978506 A US 201916978506A US 11542951 B2 US11542951 B2 US 11542951B2
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Prior art keywords
compressor
bodies
threshold value
motor
discharge pipe
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US20200400154A1 (en
Inventor
Akihiro Yamamoto
Yoshiyuki Kanemoto
Norio Aoyagi
Hiroaki Saito
Fuminori Kato
Daichi OKA
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Hitachi Industrial Equipment Systems Co Ltd
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Hitachi Industrial Equipment Systems Co Ltd
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Assigned to HITACHI INDUSTRIAL EQUIPMENT SYSTEMS CO., LTD. reassignment HITACHI INDUSTRIAL EQUIPMENT SYSTEMS CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: AOYAGI, NORIO, KANEMOTO, YOSHIYUKI, KATO, FUMINORI, OKA, Daichi, SAITO, HIROAKI, YAMAMOTO, AKIHIRO
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D27/00—Control, e.g. regulation, of pumps, pumping installations or pumping systems specially adapted for elastic fluids
    • F04D27/005—Control, e.g. regulation, of pumps, pumping installations or pumping systems specially adapted for elastic fluids by changing flow path between different stages or between a plurality of compressors; Load distribution between compressors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/06—Control using electricity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D17/00—Radial-flow pumps, e.g. centrifugal pumps; Helico-centrifugal pumps
    • F04D17/08—Centrifugal pumps
    • F04D17/10—Centrifugal pumps for compressing or evacuating
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D25/00—Pumping installations or systems
    • F04D25/02—Units comprising pumps and their driving means
    • F04D25/06—Units comprising pumps and their driving means the pump being electrically driven
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D25/00—Pumping installations or systems
    • F04D25/16—Combinations of two or more pumps ; Producing two or more separate gas flows
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D27/00—Control, e.g. regulation, of pumps, pumping installations or pumping systems specially adapted for elastic fluids
    • F04D27/02—Surge control
    • F04D27/0261—Surge control by varying driving speed
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Definitions

  • the present invention relates to a gas compressor. More particularly, the present invention relates to a method for controlling a gas compressor including a plurality of compressor bodies.
  • Patent Document 1 is a background art of a method for controlling a compressor including a plurality of compressor bodies.
  • the compressor includes the plurality of compressor bodies disposed in parallel and subjected to rotational speed control by an inverter and one main discharge flow path where the discharge flow paths of the compressor bodies converge.
  • the rotational speed control is equally performed at all times with respect to every operating compressor body for discharge pressure adjustment.
  • the operating compressor bodies are decreased in number when compressed gas supply to the main discharge flow path is excessive and it is enough to decrease the operating compressor bodies by one in number. The number is increased by one when the compressed gas supply is insufficient even after full-load operation of the operating compressor bodies.
  • Patent Document 1 JP 2002-122078 A
  • Patent Document 1 the discharge pressure of the compressor is controlled by the inverter-based rotational speed control.
  • the operating compressor bodies are N in number
  • the amount of used air decreases and a command rotational speed SO with respect to the inverter decreases.
  • SO reaches the value that is obtained by a rated rotational speed SR of a motor being multiplied by (N ⁇ 1)/N
  • the number N is controlled to be reduced to the number (N ⁇ 1).
  • Patent Document 1 does not consider the problems in the case of a sharp decrease in the amount of used air that the discharge pressure of the compressor rises more than necessary and exceeds an upper-limit pressure without the inverter-based rotational speed control being in time.
  • the present invention has been made in view of the problems, and an object of the present invention is to provide a gas compressor capable of reducing variation in discharge pressure through control of the number of compressor bodies and a control method for the gas compressor.
  • a gas compressor includes a plurality of compressor units each having a compressor body, a motor for driving the compressor body, and an inverter for controlling a rotational speed of the motor, and a control device for controlling the inverters.
  • Discharge pipes of the compressor bodies converge on one main discharge pipe. A drive frequency of the motor of each compressor body is controlled by the corresponding inverter, whereby a pressure of each discharge pipe is controlled and a discharge pressure of the main discharge pipe is controlled.
  • the control device calculates a prediction time for reaching a stopping pressure.
  • the control device stops one of the compressor bodies when the prediction time is less than a threshold value.
  • the present invention it is possible to provide a gas compressor capable of reducing variation in discharge pressure through control of the number of compressor bodies and a control method for the gas compressor.
  • FIG. 1 is a rear perspective view of a gas compressor in Example 1.
  • FIGS. 2 A to 2 C are diagrams for describing the number decrease control that is a premise of Example 1.
  • FIGS. 3 A and 3 B are diagrams for describing the principle of stopping a compressor body by the pressure prediction control that is a premise of Example 1.
  • FIGS. 4 A to 4 C are diagrams for describing the number decrease control in Example 1.
  • FIGS. 5 A to 5 C are diagrams for describing the number decrease control in Example 2.
  • FIG. 6 is a diagram for describing the number decrease control in Example 3.
  • FIGS. 7 A to 7 C are graphs for describing the relationship between the amount of use of compressed air and the rotational frequency of a compressor in Example 4.
  • the gas compressor in this example is premised on a gas compressor equipped with a plurality of compressor bodies.
  • a gas compressor that compresses air will be described as an example.
  • FIG. 1 is a rear perspective view of the gas compressor in this example.
  • FIG. 1 illustrates a state where a back panel 30 , a side panel 31 , and a top panel 32 are removed.
  • the gas compressor includes three stages of compressor units.
  • the compressor units include compressor bodies 10 , 11 , and 12 and inverters 20 , 21 , and 22 , respectively.
  • the drive frequencies of the motors (hidden and invisible in the drawing) that respectively drive the compressor bodies 10 , 11 , and 12 are controlled by the inverters 20 , 21 , and 22 , respectively.
  • a control device (hidden and invisible in the drawing) controlling each inverter is provided.
  • the discharge pipes of the compressor bodies converge on one main discharge pipe.
  • the control device controls the discharge pressure of the entire gas compressor by performing inverter-based rotational speed control on the discharge pressure of each compressor body.
  • three 7.5 KW compressor bodies can be used with respect to a gas compressor output of 22 KW.
  • FIG. 2 is a diagram for describing the number decrease control that is a premise of this example.
  • FIG. 2 is processing of decreasing the number of operating compressor bodies when the amount of used air is decreased and the amount of air is excessive even after a decrease in operating frequency.
  • (a) illustrates the discharge pressure of the gas compressor over time (hereinafter, the discharge pressure of the gas compressor, that is, the discharge pressure in the main discharge pipe will be simply referred to as the discharge pressure unless otherwise specified) and
  • (b) and (c) illustrate the drive frequencies of the motors of compressor bodies 1 and 2 (hereinafter, referred to as the drive frequencies of the compressor bodies) over time.
  • the compressor body 1 in FIG. 2 is a main machine and the compressor body 2 in FIG.
  • the discharge pressure of the gas compressor is controlled to become constant by PID control in a period TP 1 by the inverter-based rotational speed control in the two (main and following) machines.
  • the drive frequency of the compressor body is controlled to be lowered by the inverter-based rotational speed control.
  • the frequency cannot be further lowered, and thus the discharge pressure rises. There, a determination is made to decrease the number of operating compressor bodies.
  • FIG. 3 is a diagram for describing the principle of stopping the compressor body by the pressure prediction control that is a premise of this example.
  • (a) illustrates the discharge pressure of the gas compressor over time and (b) illustrates the operation/stop of the compressor body.
  • a prediction time Tu for reaching a stopping pressure (upper-limit pressure) is calculated by the following Equation (1). In other words, calculation is performed by means of the inclination information on the straight line of the increasing discharge pressure.
  • Tu ( P moff ⁇ P ( k ))/( P ( k ) ⁇ P ( k ⁇ 1)) ⁇ 1 second (1)
  • P(k) measurement pressure
  • P(k ⁇ 1) measurement pressure at preceding second
  • P moff stopping pressure
  • Tu Tu threshold value
  • the compressor body 2 (following machine) is stopped by the Tu determination, that is, the pressure prediction control and constant pressure control is started only by the main machine.
  • the Tu prediction determination is made when the discharge pressure has risen while the drive frequency of the compressor body decreases before reaching the lower-limit frequency.
  • FIG. 4 is a diagram for describing the number decrease control in this example.
  • the conditions in FIG. 4 are the same as those in FIG. 2 .
  • FIG. 4 differs from FIG. 2 in that the Tu determination is made at time T 4 when the discharge pressure has risen while the drive frequencies of the compressor bodies 1 and 2 decrease before reaching the lower-limit frequency and the compressor body 2 is stopped when the Tu threshold value exceeds Tu in (b) and (c) of FIG. 4 .
  • a rise in pressure can be suppressed early and it is possible to prevent the discharge pressure from rising due to a sharp decrease in the amount of used air.
  • FIG. 5 is a diagram for describing the number decrease control in this example.
  • the conditions in FIG. 5 are the same as those in FIG. 2 .
  • FIG. 5 differs from FIG. 2 in that the Tu determination is made when the discharge pressure has risen during operation at the lower-limit frequency and, when the Tu threshold value exceeds Tu, the compressor body 2 (following machine) is stopped at time T 5 and the constant pressure control is started only by the main machine after the frequency is raised to an operation start frequency fns after one of the compressor bodies 1 and 2 is stopped.
  • the Tu determination may be made at time T 3 that is subsequent to time T 2 as in FIG. 2 although time T 2 at which the lower-limit frequency is reached and time T 3 at which the Tu determination is made are the same in the description of this example.
  • FIG. 6 is a diagram for describing the number decrease control in this example. A case where three compressor bodies operate is illustrated as an example in FIG. 6 .
  • the prediction time Tu for reaching the stopping pressure is calculated by the above Equation (1) when the discharge pressure rises and it is determined that the rate of decrease in the amount of used air is high and a determination is made to stop the compressor body when the predetermined threshold value exceeds Tu.
  • Tu 1 and Tu 2 exceeding Tu 1 are provided and control is performed such that one compressor body (compressor body 3 ) is stopped in the case of Tu 1 ⁇ Tu ⁇ Tu 2 and two compressor bodies (compressor bodies 2 and 3 ) are stopped in the case of Tu ⁇ Tu 1 .
  • one compressor body compressor body 3
  • two compressor bodies compressor bodies 2 and 3
  • this example is not limited to the three units.
  • a plurality of Tu threshold values may be provided and a plurality of units may be simultaneously stopped in the case of three or more units.
  • a rotational frequency will be expressed as a percentage with the upper-limit frequency of the compressor body at 100% and the amount of use of compressed air will be expressed as a percentage with the amount of compressed air discharged by one compressor body operating at the upper-limit frequency at 100%.
  • the lower-limit frequency of the motor of the compressor body in this example is, for example, 60%. This is because the motor is provided with a compressor cooling fan and thus a low rotational frequency results in a decrease in the rotational speed of the cooling fan and no sufficient cooling of the compressor and a decline in compression efficiency arises from air leakage from a compression chamber and recompression in a region where the rotational frequency is low.
  • FIG. 7 shows an example of the relationship between the amount of use of compressed air and the number of activated compressor bodies and the rotational frequencies thereof.
  • FIG. 7 ( a ) is a graph showing the operation at a time when the lower-limit frequency of the compressor is 60%.
  • FIG. 7 ( b ) is a graph showing the operation at a time when operation is possible with the lower-limit frequency at 50%.
  • FIG. 7 ( c ) is a graph showing the operation at a time when operation is possible with the lower-limit frequency at 40%. It should be noted that operation is possible at a lower-limit frequency of less than 60% even in the regions of 50% to 60% and 40% to 60% in FIGS. 7 ( b ) and 7 ( c ) and yet the lower-limit frequency may be 60% as in FIG. 7 ( a ) in this region.
  • a first state where one compressor body operates at an output of 100% and a second state where two compressor bodies each operate at an output of 60% are alternately performed in a region 71 where the amount of use of compressed air is more than 100% and less than 120%.
  • operation is performed at an output of more than 100% and less than 120% on an hourly average.
  • the component service life of the second compressor body in particular may be shortened by repeated ON/OFF.
  • there is a time lag between the activation of the compressor body and target compressed air discharge and thus the followability of the discharge air amount with respect to the amount of use of compressed air may decline.
  • replacing the first and second compressors every predetermined time or every time the ON/OFF count exceeds a predetermined count is desirable in order to prevent an extreme decline in the component service life of one compressor body.
  • the problem of an increase in ON/OFF count can be addressed by means of a low-rotational speed mode that allows the compressor body to operate at a lower-limit frequency of less than 60% only when the used air amount is 100% to 120%.
  • a low-rotational speed mode that allows the compressor body to operate at a lower-limit frequency of less than 60% only when the used air amount is 100% to 120%.
  • one unit operates up to a used air amount of 100% by the compressor body being allowed to operate at a lower-limit frequency of at least 50% and it is possible to reduce the ON/OFF count of the second compressor body by two compressor bodies operating at a frequency of 50% to 60% in the case of more than 100% and less than 120%.
  • the second compressor body may be activated and the two compressor bodies may operate at a frequency of approximately 50% at a point in time when, for example, the amount of use has reached 95%.
  • the followability with respect to an increase in the amount of use is improved by setting being performed in this manner.
  • the compression efficiency may decline or the compressor body may be overheated in a situation in which the compressor body with a lower-limit frequency of 60% is operated at a frequency of 40% and thus control for lowering the lower-limit frequency needs to be narrowed down to a case where the hunting is likely to occur.
  • the hunting is likely to occur in a situation in which the amount of air used by the customer continues to be around 100%, that is, the amount of air used by the customer changes little.
  • a threshold value is set for Tu, which is a measure of the rate of change in the amount of air used by the customer, and operation is possible at a lower-limit frequency of less than 60% when Tu does not exceed the threshold value. This determination needs to be made before the second compressor body is stopped, and thus this threshold value is a value exceeding the Tu threshold value described in Example 1.
  • control for forcible cooling may be performed by increasing the rotational speed of the fan by allowing time to increase the rotation speed at regular time intervals.
  • control may be performed such that the low-rotational speed mode is released when the body temperature has become a predetermined temperature or more. It is possible to prevent the compressor body from being heated by limiting the low-rotational speed mode in this manner.
  • the low-rotational speed mode is applied when the amount of use is around 100% at which the number of operating compressor bodies is switched between one and two.
  • 100% ⁇ 2 units (200%) already exceeds 60% ⁇ 3 units (180%) and the operating ranges of the two units and the operating ranges of the three units overlap, and thus the low-rotational speed mode is unnecessary.
  • this is because there is no region corresponding to the region 71 incapable of following the amount of use of compressed air as in FIG. 7 ( a ) .
  • hunting prevention control is applicable by hysteresis being given with an increase and a decrease in the number of units as described above and this is effective for improving the component service life of the compressor body.
  • control in using the compressor body with the lower-limit frequency set to 60% has been described in this example and yet this control can be similarly performed insofar as the compressor body has a lower-limit frequency of 50% or more.
  • the numerical value such as setting the lower-limit frequency in the low-rotational speed mode to 40% and activating the second unit at a point in time when the amount of use reaches 95% during the operation of one unit is not ineffective unless it is exactly this value, the value is capable of strongly exhibiting the effect of each configuration in this example by control near this numerical value in general.
  • the present invention is not limited to the examples and includes various modification examples.
  • the examples have been described in detail so that the present invention is described in an easy-to-understand manner and are not necessarily limited to those having all the described configurations.
  • another configuration can be added, deleted, and replaced with respect to a part of the configuration of each example.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
US16/978,506 2018-09-27 2019-07-26 Gas compressor and control method therefor Active US11542951B2 (en)

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JP2018181425 2018-09-27
JP2018-181425 2018-09-27
JPJP2018-181425 2018-09-27
PCT/JP2019/029511 WO2020066268A1 (ja) 2018-09-27 2019-07-26 気体圧縮機、及び、その制御方法

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US11542951B2 true US11542951B2 (en) 2023-01-03

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US (1) US11542951B2 (zh)
EP (1) EP3859156A4 (zh)
JP (2) JP7157814B2 (zh)
CN (1) CN111771058B (zh)
WO (1) WO2020066268A1 (zh)

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0211878A (ja) 1988-06-29 1990-01-16 Toshiba Corp 車両用空気調和装置の制御方法
JPH02211878A (ja) * 1987-12-15 1990-08-23 Univ Leland Stanford Jr Ｔ−細胞活性化関連遺伝子
JPH0432903A (ja) 1990-05-23 1992-02-04 Kubota Corp 出力システム
JPH06249153A (ja) 1993-02-19 1994-09-06 Hitachi Ltd 可変容量形圧縮機
JP2002122078A (ja) 2000-10-13 2002-04-26 Kobe Steel Ltd 圧縮機の制御方法
JP2005337204A (ja) 2004-05-31 2005-12-08 Hitachi Industrial Equipment Systems Co Ltd 圧縮空気製造システム
JP2014152698A (ja) 2013-02-08 2014-08-25 Hitachi Industrial Equipment Systems Co Ltd 流体圧縮システム
JP2014152699A (ja) 2013-02-08 2014-08-25 Hitachi Industrial Equipment Systems Co Ltd 流体圧縮システム

Family Cites Families (1)

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Publication number Priority date Publication date Assignee Title
JP3064786B2 (ja) * 1994-01-31 2000-07-12 株式会社日立製作所 ポンプ装置

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02211878A (ja) * 1987-12-15 1990-08-23 Univ Leland Stanford Jr Ｔ−細胞活性化関連遺伝子
JPH0211878A (ja) 1988-06-29 1990-01-16 Toshiba Corp 車両用空気調和装置の制御方法
JPH0432903A (ja) 1990-05-23 1992-02-04 Kubota Corp 出力システム
JPH06249153A (ja) 1993-02-19 1994-09-06 Hitachi Ltd 可変容量形圧縮機
JP2002122078A (ja) 2000-10-13 2002-04-26 Kobe Steel Ltd 圧縮機の制御方法
JP2005337204A (ja) 2004-05-31 2005-12-08 Hitachi Industrial Equipment Systems Co Ltd 圧縮空気製造システム
JP2014152698A (ja) 2013-02-08 2014-08-25 Hitachi Industrial Equipment Systems Co Ltd 流体圧縮システム
JP2014152699A (ja) 2013-02-08 2014-08-25 Hitachi Industrial Equipment Systems Co Ltd 流体圧縮システム

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Title
English Translation of JP-2014152698-A obtained Nov. 3, 2021 (Year: 2021). *
Extended European Search Report issued in European Application No. 19868014.2 dated Sep. 28, 2022 (eight (8) pages).
Hindi-language Office Action issued in Indian Application No. 202017039181 dated Apr. 28, 2021 with English translation (6 pages).
International Search Report (PCT/ISA/210) issued in PCT Application No. PCT/JP2019/029511 dated Oct. 15, 2019 with English translation (two (2) pages).
Japanese-language Office Action issued in Japanese Application No. 2020-548071 dated Jun. 1, 2021 (2 pages).
Japanese-language Office Action issued in Japanese Application No. 2020-548071 dated Oct. 5, 2021 with English translation (seven (7) pages).
Japanese-language Written Opinion (PCT/ISA/237) issued in PCT Application No. PCT/JP2019/029511 dated Oct. 15, 2019 (four (4) pages).

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US20200400154A1 (en) 2020-12-24
WO2020066268A1 (ja) 2020-04-02
JP2022145796A (ja) 2022-10-04
EP3859156A1 (en) 2021-08-04
JP7157814B2 (ja) 2022-10-20
EP3859156A4 (en) 2022-10-26
CN111771058B (zh) 2022-10-25
CN111771058A (zh) 2020-10-13
JPWO2020066268A1 (ja) 2021-02-15
JP7410238B2 (ja) 2024-01-09

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